Three distinct chromatin domains in telomere ends of polytene chromosomes in Drosophila melanogaster Tel mutants

Evgenia N. Andreyeva, Elena S. Belyaeva, Valerii F. Sameshin, Galina V. Pokholkova, Igor F. Zhimulev

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

Drosophila melanogaster telomeric DNA is known to comprise two domains: the terminal tract of retrotransposons (HeT-A, TART and TAHRE) and telomere-associated sequences (TAS). Chromosome tips are capped by a protein complex, which is assembled on the chromosome ends independently of the underlying terminal DNA sequences. To investigate the properties of these domains in salivary gland polytene chromosomes, we made use of Tel mutants. Telomeres in this background are elongated owing to the amplification of a block of terminal retroelements. Supercompact heterochromatin is absent from the telomeres of polytene chromosomes: electron microscopy analysis identifies the telomeric cap and the tract of retroelements as a reticular material, having no discernible banding pattern, whereas TAS repeats appear as faint bands. According to the pattern of bound proteins, the cap, tract of retroelements and TAS constitute distinct and non-overlapping domains in telomeres. SUUR, HP2, SU(VAR)3-7 and H3Me3K27 localize to the cap region, as has been demonstrated for HP1. All these proteins are also found in pericentric heterochromatin. The tract of retroelements is associated with proteins characteristic for both heterochromatin (H3Me3K9) and euchromatin (H3Me3K4, JIL-1, Z4). The TAS region is enriched for H3Me3K27. PC and E(Z) are detected both in TAS and many intercalary heterochromatin regions. Telomeres complete replication earlier than heterochromatic regions. The frequency of telomeric associations in salivary gland polytene chromosomes does not depend on the SuUR gene dosage, rather it appears to be defined by the telomere length.

Original languageEnglish (US)
Pages (from-to)5465-5477
Number of pages13
JournalJournal of cell science
Volume118
Issue number23
DOIs
StatePublished - Dec 1 2005
Externally publishedYes

Keywords

  • Drosophila
  • Heterochromatin
  • Silencing
  • Telomeres
  • Telomeric Associations

ASJC Scopus subject areas

  • Cell Biology

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